== Amstrad PCW ==
The Amstrad PCW has a 50-pin Expansion port, too. But it's its pin-outs are entirely different as on CPC.
* [[Amstrad PCW Expansion Port]]
==Signal Descriptions==
* A15-A0 (Address bus; Output from CPU). A15-A0 form a 16-bit address. A15-A0 are used to specify a memory address or an I/O address.
* /BUSAK (Bus Acknowledge; Output from CPU). When /BUSAK="0" the CPU is signalling that control of the address bus, data bus and output signals has been released, and the device can take control.
* /BUS RESET (Bus Reset; Input to ???PIO/CPU)??Acts similarly to /RESET but also resets the PIO chip.
* /BUSRQ (Bus Request; Input to CPU). When /BUSRQ="0" a device is requesting control of the address bus, data bus and the CPU's output signals. At the end of the current instruction cycle, the CPU will issue a Bus Acknowledge.
* CURSOR (Cursor; Output from CRTC). When CURSOR="1" the CRTC is displaying the cursor.
** A expansion device (e.g. a ROM-board) can use this signal to activate the selected ROM plugged into the device.
* Sound (Mono Audio; Output from PSG). This is a mono audio signal generated by mixing the 3 PSG audio channels together.
* /WAIT (Ready / Wait; Input to CPU, Output from Gate-Array). When /WAIT="0" this signal is used to delay memory or I/O access by the CPU. This signal is used to force the CPU to access memory or I/O when it is ready. This signal is generated by the Gate-Array.
* /WR (Write; Output from CPU). When /WR="0" the CPU is performing a write operation. The operations are:
** Writing to a I/O device: (/IORQ="0", A15-A0 contain I/O address)